Date of Award

2023

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Chemical Engineering (MS)

Administrative Home Department

Department of Chemical Engineering

Advisor 1

Caryn Heldt

Committee Member 1

Rebecca Ong

Committee Member 2

Bruce Lee

Abstract

The development of virucidal coatings to inactivate a broad spectrum of viruses has gained popularity. Antiviral coating of personal protective equipment such as facial coverings can reduce the accumulation of viral load and mitigate transmission of airborne illnesses, which occur primarily through direct contact with respiratory aerosols or droplets carrying infectious viruses. Moreover, modification of PPE to inactivate viruses upon contact improves their reusability and reduces waste. Coating high frequency touch surfaces with similar virucidal coatings can reduce the risk of disease transmission associated with contaminated surfaces. This study explores the development of three novel virucidal materials to control the spread of viruses which occur either through direct or indirect exposure.

Naturally occurring zeolites and clay minerals such as vermiculite and sepiolite find use in polymer composites to enhance material properties. They are highly absorbent and due to their large cation-exchange capacity, provide a great platform to incorporate virucidal metal ions such as silver, zinc, copper and iron. Here, two novel antiviral clay mineral powders, vermiculite, and sepiolite, were decorated with a powerful antiviral agent, cupric ion (Cu2+). The modified vermiculite powders showed 2.6 and 2.5 log-reduction in the titer of the non-enveloped PPV and enveloped HCoV 229E, respectively, by inactivation in 2 hours at 4 ℃. Sepiolite reduced the titers of PPV and HCoV by 3.5 and 3.2 log10 respectively, either through inactivation or virus adsorption or both. Adsorption of virus to the surface of the powder was determined to be crucial for inactivation by Cu2+.

Quaternary ammonium (QA) compounds find use commercially and domestically to inactivate a broad spectrum of disease-causing viruses. Melt-blown polypropylene (mbPP), used as the main filtration layer in the WHO approved N95 mask and spun-bound polypropylene (sbPP), utilized in surgical masks were covalently and physically functionalized with a C12 quaternary ammonium compound - benzophenone. QA grafting of mbPP resulted in the largest reversal of surface charge density. The same fabric was found to be most effective in lowering the titer of enveloped viruses SuHV-1 and HCoV 229E by 3.3 and 2.3 log10 respectively. However, functionalization of the fabric led a decreased thein filtration efficiency to ~50% which was resolved by using the less effective sbPP as an outer layer in a prototype 3-ply N95 mask model.

Hydrogen peroxide (H2O2), a strong oxidizing agent, is another disinfectant commonly used in industry and households to meet daily disinfection needs. H2O2 releases a highly reactive hydroxyl free radical which can disrupt a broad spectrum of biomolecules such as proteins, nucleic acids and lipids to inactivate viruses. The catechol functional group in 6-hydroxydopmine (6-OHDA) generates H2O2 as a by-product when exposed to moisture. Here, polyacrylamide (PAAm) copolymerized with 6-OHDA was coated onto non-woven mbPP fabrics while maintaining fabric porosity at 80%. Sustained release of H2O2 with catechol copolymerized mbPP fabrics was demonstrated over a 24-hour period at room temperature. The fabrics were found to show 2.2 and 1.1 log-reduction in the titer of BVDV and HCoV respectively at room temperature.

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